The present invention relates to a cutting tool, and more particularly, to a device that can be used to cut an installed portion of well pipe or well casing from the inside of the pipe or casing.
Recently promulgated regulations pertaining to groundwater well construction have placed a burden on well drillers to install outer metal pipe casings at the upper portion of a groundwater well. The casing may extend some depth, and depending upon site conditions, the casing may extend through upper soil deposits and into a non-water bearing soil or rock formation. Drilling is subsequently performed through the center of the outer metal casing, and typically includes the installation of an inner pipe that extends into a deeper water bearing formation.
For a number reasons, the well driller may desire to cut either the pipe or casing after it has been installed in a borehole. For example, the well driller may be tasked with installing a pitless adapter below the frost depth, thereby allowing the well to convey water to a horizontal water supply pipe that is also installed below frost depth.
Down hole pipe cutters of the prior art are typically complicated and offer the operator limited control over the device. For example, U.S. Pat. No. 4,369,573 to Vitale discloses a pipe cutter for cutting the wall of a pipe from within the bore of a pipe. The blade is mounted on an eccentric axis at the base of a drive body. However, the device disclosed in Vitale utilizes a xe2x80x9cgripperxe2x80x9d portion that acts in conjunction with the torque of the spinning blade to rotate the blade within the pipe, thereby causing the rotating blade to traverse the circumference of the pipe. This type of circumferential rotation mechanism limits operator control of the device while it is cutting the inner circumference of the pipe or casing.
U.S. Pat. No. 1,068,991 to Dunkerley et al. discloses a flue cutter that utilizes a knife that is flung out against the flue when the tool is rotated rapidly. The Dunkerley device does not provide an eccentrically mounted blade that is urged toward the pipe or casing wall in a controlled manner. Furthermore, the Dunkerley device fails to provide means for supporting the cut section of pipe while the cut section is being extracted from the borehole.
U.S. Pat. No. 3,783,721 to Miller discloses a tube cutter that is placed inside a tube and rotated using a hand drill to cut the tube. The Miller device is not suited for down hole pipe cutting because the depth of use is limited by the diameter of the pipe being cut. Furthermore, it is possible to over cut the inner pipe and potentially cut through the outer pipe wall, if present.
U.S. Pat. No. 4,576,070 to Fitzgerald discloses a pipe cutter powered by a hand held tool that is used to cut the pipe from the pipe""s interior. Like the Miller reference, this reference is not suited for down hole cutting because the depth of use is limited by the diameter of the pipe being cut. More specifically, the cutting element must by maintained in a straight line orientation with the hand held tool thus limiting the ability of a user to traverse the cutting unit around the circumference of the pipe in a controlled manner.
U.S. Pat. No. 4,809,775 to Fortin discloses a down-hole pipe recovery cutting tool using compressed air to power a motor located near the cutting blade. The Fortin device uses a centralizer that is thrown off into the well after the cutting toot is activated. This could detrimentally impact the condition of the well by blocking the deeper pipe, therefore preventing future installation of a submersible pump. In addition, even if the centralizer happens to fall to the bottom of the well, the centralizer will nonetheless prevent access to the bottom of the well screen.
U.S. Pat. No. 4,932,125 to Poveromo discloses a device that can be used to cut a pipe from its interior. Poveromo uses a blade that is not eccentrically mounted. Instead, the blade is mounted on a rigid shaft with a flange that is pushed by hand around the interior of the pipe, thus cutting the pipe.
U.S. Pat. No. 6,125,929 to Davis et al. discloses a down-hole casing cutting tool. Davis et al. discloses longitudinal cutting blades that are spun by rotating the drill rod of a large gas or oil drilling rig. The Davis et al. device is fairly complex and does not lend itself to simple and quick use.
In view of the above, there is a long felt but unsolved need for a down hole pipe cutting tool that avoids the above-mentioned deficiencies of the prior art and that provides an effective system that is relatively easy to use and that can be produced at a reasonable cost. Accordingly, the limitations of the prior art are addressed by the present invention discussed below.
In accordance with the present invention, a down hole pipe and casing cutter is provided. One unique feature of the invention is its ability to be utilized on an installed section of pipe that is set within a borehole, while giving the operator control over how the blade is urged into contact with the pipe wall and rotated about the circumference of the pipe to cause a complete cut. In operation, a borehole is first drilled in the earth, followed by the installation of a pipe within the borehole, such as a metal casing or a plastic well pipe. Subsequently, the invention is placed within the uppermost portion of the installed pipe that is desired to be cut, and the device is used to cut a desired length of the uppermost portion of the pipe. The device is then removed along with the cut portion of pipe.
The device is principally comprised of three main sections: (1) a lower section, (2) a middle section, and (3) an upper section. The lower section has a positioning disc and a cutting blade. The positioning disc is sized to fit the diameter of the pipe being cut. It is lowered into the pipe and is connected to the upper section by the middle section. The cutting blade is eccentrically positioned below the bottom of the positioning disc. The diameter of the cutting blade is substantially smaller than the diameter of the pipe being cut. The cutting blade can be moved between a first retracted position and a second extended cutting position. The positioning disc maintains the cutting blade position relative to the surrounding pipe wall.
The middle section may be of various lengths. Typically, a 10 foot section is used in the field for groundwater well applications; however longer lengths such as 12, 15 or 20 feet are easily used. Furthermore, the present invention has application to the plumbing industry where pipes of shorter lengths are encountered. Thus, the middle section might be only 8, 12, 24, or 36 inches long. The middle section includes a connection rod and a blade drive stem. The connection rod is simply a section of rod that connects the upper section to the lower section. The blade drive stem has an outer tubular member and an inner rod that rotates the blade.
The upper section has a positioning plate, drill linkage, and a handle to rotate the device within the pipe. The positioning plate fits over the top of the pipe, and keeps the device centered at the top of the pipe. The drill linkage allows a power source, preferably a hand drill, to be attached to the inner rod of the blade drive stem. The handle allows the entire device to be rotated within the pipe, thereby causing the entire circumference of the pipe to be cut.
In a preferred method of use, the cutting blade is first placed in its retracted (non-cutting/unexposed) position. Then the operator lowers the device into the pipe such that the lower section is positioned at the location where the pipe is desired to be cut. A hand-held power tool is mounted to the upper section and attached by the drill linkage to the inner rod of the blade drive stem. The power tool is turned xe2x80x9conxe2x80x9d to spin the blade. The outer tubular member of the blade drive stem is then manually rotated by the operator using a first handle interconnected thereto, thus bringing the eccentrically mounted spinning blade into contact with the pipe wall. This rotation causes a small portion of the pipe wall circumference to be cut. While still spinning, the blade is then locked in this outer cutting position by locking the first handle in place. A second handle on the upper section is then turned by the operator through a path of 360 degrees, thereby causing the entire device to rotate within the pipe, which in turn causes the spinning blade to cut the entire circumference of the pipe. The power tool may then be turned xe2x80x9coff.xe2x80x9d With the pipe wall now entirely cut, and without retracting the blade, the entire device is removed from the borehole. The cut section of pipe is also removed because the blade extends beyond the pipe wall, thereby supporting the pipe when removing the device from the borehole.
The above and other aspects of the invention are realized in a specific illustrated embodiment of the invention discussed below in conjunction with the drawings.